Assessing ongoing sources of dissolved‐phase polychlorinated biphenyls in a contaminated stream

Abstract

Abstract-Few studies assess the potential of ongoing sources of ''fresh'' polychlorinated biphenyls (PCBs) to aquatic systems when direct discharge to the environment has been eliminated. In the present study, the authors used single-layered, low-density polyethylene samplers (PEs) to measure total PCB concentrations, congener profiles, and enantiomeric fractions (EFs) in a contaminated stream and to provide multiple lines of evidence for assessing ongoing inputs of PCB. Concentrations were well above background levels that have been monitored for years. Concentrations significantly increased with distance, the farthest downstream PE concentrations being almost five times greater than those at 79 m downstream of a historical point source. The PCBs in the PEs at 79 m downstream of the contamination source were dominated by low K OW congeners, similar to those in the mixture of Aroclors 1016 and 1254 (4:1 v/v) historically released from the former capacitor manufacturer. The only two chiral congeners detected in the PEs downstream were PCBs 91 and 95. The EF values were nonracemic for PCB 91, while the values were either racemic or near racemic for PCB 95. Increased PCB concentrations with distance and a congener composition of predominantly low-weight congeners in the PEs at 79 m downstream of the plant site suggested an ongoing PCB source from the plant site. Chiral signatures suggested aerobic biotransformation of dissolved PCBs but did not shed any light on possible ongoing PCB inputs. Environ. Toxicol. Chem. 2013;32:535-540. # 2012 SETAC

Assessing atmospheric concentration of polychlorinated biphenyls by evergreen Rhododendron maximum next to a contaminated stream

“…In contrast, PCBs in soil samples were detected at concentrations of 481.9 ± 101.7 ng g −1 dry weight suggesting a potential source to rhododendron from surficial soils. Dissolved PCBs were also measured in Town Creek using PE samplers and concentrations averaged 2110 ± 103.7 ng g −1 PE . In addition, Dang et al indicated that the presence of di‐CBs in PEs indicates a potential fresh source (e.g., groundwater input via seepage in fractured rock or soil erosion from land) in the vicinity of the former wastewater treatment plant rather than the sources from a Sangamo–Weston site.…”

“…Dissolved PCBs were also measured in Town Creek using PE samplers and concentrations averaged 2110 ± 103.7 ng g −1 PE . In addition, Dang et al indicated that the presence of di‐CBs in PEs indicates a potential fresh source (e.g., groundwater input via seepage in fractured rock or soil erosion from land) in the vicinity of the former wastewater treatment plant rather than the sources from a Sangamo–Weston site. In the present study, nonmetric multidimensional scaling data showed that homolog distributions in rhododendron and PEs were relatively similar and dominated by lower chlorinated congeners (e.g., di‐CBs + tri‐CBs, tetra‐CBs; Figure ).…”

“…The value of K AW was temperature dependent; therefore, temperatures were also taken into account to estimate BCF V at different sampling seasons (Supplemental Data, Table S1). Results from dissolved PCBs in the stream adjacent to the rhododendron were acquired from a previous study using polyethylene (PE) passive samplers [25]. The PE samplers were deployed from December 2010 to February 2011 at 8 locations ranging from 79 m to 3000 m downstream from the Sangamo-Weston site as described by Dang et al [25].…”

“…Results from dissolved PCBs in the stream adjacent to the rhododendron were acquired from a previous study using polyethylene (PE) passive samplers . The PE samplers were deployed from December 2010 to February 2011 at 8 locations ranging from 79 m to 3000 m downstream from the Sangamo–Weston site as described by Dang et al . Data from Town Creek deployments (3 samples at each site) were used in the present study.…”

“…Historically, the site was contaminated with PCBs discharged from a former Sangamo–Weston capacitor manufacturing plant in Pickens, South Carolina (USA) . Although the active discharge from the Sangamo–Weston site was discontinued in 1997, ongoing sources (e.g., input from the former wastewater treatment plants, ground water input via seepage in fractured rock, or soil erosion from land) are still delivering dissolved PCBs to the stream system . These dissolved PCBs can cross the water–air interface and further accumulate in rhododendron leaves growing in the vicinity of the stream.…”